Water changes will dilute some nitrates in your water, but the underlying problem of why you have the nitrates is still there. You need to find the cause to address it.
What type of media do those filters you mention use and what is your cleaning schedule for them? What type of substrate are you using? Do you have LR and, if so, how much and what kind? How many fish in the tank, and what size tank? What do you have in the tank for water circulation? Do you have a lot of micro algae problems? I'm assuming no corals or inverts as they wouldn't survive in tank with that much nitrate.
The reason you have high nitrates is because your system is failing at nutrient export. This means that the nutrients or organics going into your tank, like uneaten food, fish waste, etc., is not being efficiently processed, or exported from your system--thus, you have the byproduct [nitrate]. Ideally, a tank that is well-balanced will be able to filter the nutrients coming into the system enough so that there is no ammonia, no nitrite, and little or no nitrate. Obviously, your system is not efficient enough to complete the export process. You need to find the reason why, or spend your entire hobby exp with high nitrates, a less than healthy system and doing a lot of water changes that never seem to resolve the problem.
How is your refugiumset up?
Have you or your husband studied up on aquarium keeping? Read any books, etc.?
